The present invention relates generally to systems for viewing scenes, especially low light level or inaccessible scenes, and more particularly to systems for providing an enhanced view of a scene on a display for a viewer.
In recent years thermal imaging systems, based on uncooled detector arrays, have become an important aid in driving at night time and under adverse weather and battlefield conditions. Some systems are now available, mostly known as driver viewer enhancement or driver vision enhancing (DVE) systems. The DVE systems normally have a sensor module (SM) which produces a processed and corrected video image in analog form (RS 170 or other formats). The video image is presented on a display unit, sometimes referred to as display and control module (DCM). The DVE systems for military applications use prisms, mirrors and similar optical elements deviating one or more times, the radiation path from the scene to the sensor.
There is a demand for smaller and less costly thermal imaging systems. It is desirable that the SM be as small as possible to allow maximum flexibility in mounting the unit in armored vehicles, tactical wheeled vehicles and commercial vehicles. It is an advantage to reduce the cost of the system, especially cost driving components such as system optics.
The present invention provides solutions to the above problems by employing a unique system architecture which results in a very small SM, while using available technologies such as conventional optics and uncooled micro bolometer detector arrays. In this architecture there is a complete separation between the SM and the digital image processing unit, which is housed in the DCM. The present invention utilizes only refractive optical elements in a straight line radiation path from scene to sensor. This design allows the SM to be a very small unit relative to other existing sensor modules and benefits in improved performance.
The system of the present invention can be used in a variety of applications including a driving aid for various types of vehicles, mast mount sensors with remote display and control unit, helmet mounted sensors for fire fighting, soldiers, etc., and marine observation, railroad cars and other safety related remote monitoring applications. Additionally, the SM provides a xe2x80x9cforward lookingxe2x80x9d system which is one in which all the optical elements are on the same optical axis oriented towards the scene to be imaged, as opposed to a periscopic system in which the optics are folded.
The DVE system is designed to work in a variety of host military vehicles, including combat vehicles and tactical wheeled vehicles. A partial list of vehicles include the LAV, Bradley, Abrams, M113, heavy equipment transport systems, heavy expanded mobility tactical trucks and high mobility multi-purpose wheeled vehicles. The DVE interface may be adapted to other families of combat and tactical vehicles, as well as commercial vehicles, marine vessels, etc.
In order to minimize the size of the sensor module, a new system concept has been developed. The SM contains only the necessary components that must be in direct view with the observed scene, i.e. optics, detector array and minimal required electronics. The rest of the electronics, including the image processing unit, are housed in the DCM. This desirable separation required technical solutions in order to make the system operational.
In accordance with one form of the invention, an image of a scene is acquired based on the infrared radiation emanating from the scene and the scene image is displayed at a location removed from the site of image acquisition by first projecting the scene infrared radiation onto an array of infrared sensitive elements. An infrared radiation level indicative analog signal is derived from each array element. Each analog signal is converted into a digital representation and transmitted to the display location where the digital representations are utilized to energize a correspondingly located element of a display device. The system and process include sensor array calibrating and other statistical processing performed at the display location. The present invention comprises a thermal imager system comprising an uncooled microbolometer detector array and optics of a sensor module separate from an image processing and display unit, thereby providing a small, direct view sensor module that may be oriented for forward viewing.